Yes it is snowing today in Reykjavik,a very cold polar air is flowing south.
it is caused by an 978 mbr low north east of Iceland.
after a warmest summer in 140 years,the shift is very harsh.
a week ago it was 15°c and almost full summer.
the temp in Reykjavik 3 a clock today is only 4,2°c.
at Akureyri only 1°c at the same time
Kirkjubæjarklaustur 8°c
the snow did melt at once it hit the green grass.
the trees where in full leaves when the north blitz began
only a faint fall color by some species.
they look rather porly now.
and some were blown down by strong wind force like a
10 meter high aspen trees in Akureyri.

so enjoy your 26°c in London.

Thor,Iceland

http://www.wetterzentrale.de/pics/bracka.html
http://www.vedur.is/english/